'istioctl verify-install' improper default of Istio namespace (#29411)
'istioctl verify-install' improper default of Istio namespace (#29411)

* 'istioctl verify-install' should default Istio namespace

* Only show error if there is one

* Colorize output and remove duplicate output

* Do not colorize '!' in verify-install
istio/istio,istio/istio,istio/istio,istio/istio,istio/istio